For convenience purposes, it is well known to provide garage doors which utilize a motor to provide opening and closing movements of the door. Motors may also be coupled with other types of movable barriers such as gates, windows, retractable overhangs and the like. An operator is employed to control the motor and related functions with respect to the door. It is also known to provide safety devices that are connected to the operator for the purpose of detecting an obstruction so that the operator may then take corrective action with the motor to avoid entrapment of the obstruction.
There are three basic types of transmitters that can be used to instruct an operator to initiate a desired action. A portable or remote transmitter is usually kept in the user's vehicle and allows the user to open and close the door from inside the vehicle. The portable transmitter may have several buttons, wherein each button is associated with operation of a different door. A wall station transmitter is usually mounted near an interior door of the garage and allows the user to open and close the garage door as needed. The wall station may include function buttons to allow programming of the operator, delay closing of the door, setting of a pet height and other functions. The other type of transmitter is a keypad, which is typically mounted outside the garage, that requires manual entry of a code prior to sending an open/close signal. These remote devices may also be provided with additional features such as the ability to control multiple doors, lights associated with the doors, and other security features.
In order for a transmitter device to work with an operator to control movement of the garage door, the operator must be programmed to learn the particular serial number code for each transmitter. In the past, radio controls utilized a code setable switch, such as a ten-circuit DIP switch to set the data for both the transmitter and the receiver. Both the transmitter and the receiver's code switch must match for the transmitter to activate the receiver's output. This method did not allow for enough unique codes and was relatively easy for someone to copy the code and gain improper access. Accordingly, this process required the setting of transmitter and receiver codes physically switched to identical settings for operation of the garage door.
Presently, most radio controls for garage doors use either a fixed code format wherein the same data for each transmission is sent, or a rolling-code format, wherein some or all of the data changes for each transmission. A fixed code transmitter, also known as a fixed address or a fixed serial number transmitter, is assigned and factory programmed into a transmitter's non-volatile memory during the manufacturing of the product. A receiver is designed to “learn” a transmitter's code and the transmitter's code is stored in the receiver's non-volatile memory. This increased the number of possible codes (from 1024 or 19,683 to millions) and eliminated the DIP switch. This also prevented the code from being visible, as is the case with the DIP switch transmitter, thus preventing theft of the code.
A rolling code transmitter is similar to a fixed code transmitter, but at least a portion of the address, also known as the code or serial number, is changed with every operation of the transmitter. The transmitter and the corresponding receiving unit use an algorithm to determine what the next code to transmit/receive shall be. Only the proper code will activate the receiver.
As is well documented in the art, there are several different ways to program an operator so that it is responsive to a transmitter. One method of entering a program mode is to actuate a button directly associated with the operator and then actuate a transmitter button so that the operator learns the transmitter's serial number. Regardless of how a serial number is learned, the operator stores the number as entered. Problems arise in programming new transmitters when the memory of the operator is completely filled with transmitter serial numbers. In known operator systems, the operator simply overwrites previously stored transmitter codes. This is problematic when a wall station transmitting code is overwritten or deleted since the wall station transmitter includes extra functions utilized for operation of the garage door operator system. Therefore, there is a need in the art to ensure that wall station transmitter codes are not inadvertently deleted when programming a new transmitter code for use with the operator.